Does anyone know how to make a manga reader on drupal? this site did it http://www.ismanga.com/5-centimeters-second-11 I'm wondering how to mimic that site
Very easily, that is an awful implementation of Drupal without any real customisations. It's just an image. Create a new article, insert an image, done. Maybe you mean the multi page? You could create "books" (it's a core module, but disabled by default) or using the Paging module: https://drupal.org/project/paging It is in the downloads list, just an alpha release (there is a dev version too).
It is a multipage node. As I mentioned, you can use the Paging module, which allows customisations to the paging. Do this from within your theme (a template for the Manga content type). Search Google for examples of using theme_pager().